Stein branded 28mm internal diameter aluminum anchor ring made exclusively by ISC Wales from 7075 T6 aluminum for strength, durability and lightness. The outer diameter is 52mm and the bar is 12mm. Anodized in Stein 'Blue' to help differentiate from the small and large ring when viewed from a distance. eg on a cambium saver in a tree. 100% inspected and proof tested to 16kN. Multiple uses for tree climbers from friction savers to SRT anchors.